Will this affect the story and how tall will Sherlock's hat rise?

Moffat said the special would not have any impact on the ongoing Sherlock series.

"The special is its own thing. We wouldn't have done the story we're doing, and the way we're doing it, if we didn't have this special. It's not part of the run of three episodes. So we had this to do it – as we could hardly conceal – it's Victorian. [Co-creator Mark Gatiss] and me, we wanted to do this, but it had to be a special, it had to be separate entity on its own. It's kind of in its own little bubble."

As far away as Last November, the BBC hinted at such a departure back to the source material with a not-so-subtle tweet.